This invention relates to a portable apparatus for surface treatment with particulate material projected at high velocity onto the surface. More particularly, it relates to a portable self-contained device including means for the removal of particulate material, dust, rubber and other debris from a vehicular surface such as a highway or airplane runway. Such surface treatment is effective for cleaning the vehicular surface and otherwise restoring vehicle traction characteristics thereon.
In U.S. Pat. No. 3,691,689, description is made of a mobile apparatus for cleaning surfaces with a particulate abrasive material wherein the abrasive particles are thrown centrifugally at high velocity downwardly through the open bottom side of a housing enclosing an exposed surface to be cleaned. The particulate material thrown onto the surface at a high velocity is prevented from ricocheting into the atmosphere by an apron of resilient material which reaches down to the surface. The spent particulate material and dust pass under the apron for subsequent removal from the surface by a rotating brush. The brush sweeps the particulate material and dust into an elevator which raises the dust and particulate material to a separator whereby the particulate material is separated from the dust and returned for recycling by the throwing wheel.
The brush pickup of the above referenced patent represents an extra piece of equipment which materially increases the size of the machine and cost of operation. Further, the brushes require frequent replacement and do not accomplish a fully satisfactory recovery of the particulate and debris. This is particularly true when operating over a rough, uneven or grooved surface.
Another method of surface treatment is disclosed in U.S. patent application Ser. No. 363,723 filed May 24, 1973 now U.S. Pat. No. 3,877,175, issued Apr. 15, 1975, and assigned to the present assignee. There a vacuum type recovery system is employed wherein jets of air are directed towards the surface to focus and elevate spent abrasive and debris towards a vacuum inlet wherein a suction force is effective for picking up the debris and abrasive. While this technique is more efficient than disclosed in the referenced patent, it is incapable of effective removal of abrasive trapped in cracks or grooves in a vehicular surface. This is a particularly troublesome problem in the case of airport runways which are often systematically grooved to increase the coefficient of friction of the surface and to improve its water runoff capabilities. If the equipment is not capable of adequately removing abrasive from a grooved pavement, there is a slow but perceptible buildup of such material in the grooves, reducing traction and water runoff.
In U.S. patent application Ser. No. 432,353, filed Jan. 10, 1974, now U.S. Pat. No. 3,858,359, issued Jan. 7, 1975, and also assigned to the present assignee, there is disclosed a third type of mobile surface treating apparatus wherein the recovery means employed is magnetic. In this apparatus the abrasive thrown onto the surface is ferromagnetic as, for example, steel shot or grit. The shot or grit is recovered by use of a magnetic drum positioned rearwardly of the throwing wheel sufficiently close to the surface that the abrasive is attracted thereto. After pickup the abrasive is conveyed to a belt and bucket elevator for subsequent cleaning and reuse. This technique provides a high recovery rate of abrasive regardless of whether the abrasive is on a flat surface or in cracks or grooves on said surface. However, it can remove only ferromagnetic material and leaves much dust, rubber and other nonmagnetic debris in place. Accordingly, it is again necessary to provide additional cleaning equipment to insure complete removal of the nonmagnetic debris.
Other methods of particulate pickup utilizing magnetic or vacuum means or which employ rebound techniques are described in the following U.S. Pat. Nos. 3,380,196 (Mabille); 2,064,344 (Good); 3,004,279 (Ringer); 3,034,262 (Paulson); and 3,448,544 (Cardone).
Accordingly, it is an object of the present invention to provide a portable surface treating apparatus which is capable of substantially completely removing both magnetic and nonmagnetic debris from a road surface whether grooved or flat.
It is another object of the present invention to provide a portable surface treating apparatus capable of recovering all debris and particulate from a surface.
It is a further object of the present invention to provide a portable surface treating apparatus capable of removing debris from grooved and cracked surfaces.
It is still another object of the present invention to provide a portable surface treating apparatus capable of continuous operation over a substantial period of time.
It is yet another object of the present invention to provide a portable surface treating apparatus which achieves economy of operation by recovery and reuse of abrasive.
It is a further object of the present invention to provide a portable surface treating apparatus capable of off-loading debris to a dumping vehicle to minimize downtime.
Other objects and advantages of the invention will be apparent from the concluding portion of the specification.